CFG.h revision 2fbfdcffd3e0cf41422aaa6c526c37cb02b81341 
1//===-- llvm/Support/CFG.h - Process LLVM structures as graphs ---*- C++ -*--=//
2//
3// This file defines specializations of GraphTraits that allow Function and
4// BasicBlock graphs to be treated as proper graphs for generic algorithms.
5//
6//===----------------------------------------------------------------------===//
7
8#ifndef LLVM_CFG_H
9#define LLVM_CFG_H
10
11#include "Support/GraphTraits.h"
12#include "llvm/Function.h"
13#include "llvm/BasicBlock.h"
14#include "llvm/InstrTypes.h"
15#include <iterator>
16
17//===--------------------------------------------------------------------===//
18// BasicBlock pred_iterator definition
19//===--------------------------------------------------------------------===//
20
21template <class _Ptr,  class _USE_iterator> // Predecessor Iterator
22class PredIterator : public std::bidirectional_iterator<_Ptr, ptrdiff_t> {
23  _Ptr *BB;
24  _USE_iterator It;
25public:
26  typedef PredIterator<_Ptr,_USE_iterator> _Self;
27
28  inline void advancePastConstants() {
29    // TODO: This is bad
30    // Loop to ignore constant pool references
31    while (It != BB->use_end() && !isa<TerminatorInst>(*It))
32      ++It;
33  }
34
35  inline PredIterator(_Ptr *bb) : BB(bb), It(bb->use_begin()) {
36    advancePastConstants();
37  }
38  inline PredIterator(_Ptr *bb, bool) : BB(bb), It(bb->use_end()) {}
39
40  inline bool operator==(const _Self& x) const { return It == x.It; }
41  inline bool operator!=(const _Self& x) const { return !operator==(x); }
42
43  inline pointer operator*() const {
44    assert(It != BB->use_end() && "pred_iterator out of range!");
45    return cast<Instruction>(*It)->getParent();
46  }
47  inline pointer *operator->() const { return &(operator*()); }
48
49  inline _Self& operator++() {   // Preincrement
50    assert(It != BB->use_end() && "pred_iterator out of range!");
51    ++It; advancePastConstants();
52    return *this;
53  }
54
55  inline _Self operator++(int) { // Postincrement
56    _Self tmp = *this; ++*this; return tmp;
57  }
58
59  inline _Self& operator--() { --It; return *this; }  // Predecrement
60  inline _Self operator--(int) { // Postdecrement
61    _Self tmp = *this; --*this; return tmp;
62  }
63};
64
65typedef PredIterator<BasicBlock, Value::use_iterator> pred_iterator;
66typedef PredIterator<const BasicBlock,
67                     Value::use_const_iterator> pred_const_iterator;
68
69inline pred_iterator pred_begin(BasicBlock *BB) { return pred_iterator(BB); }
70inline pred_const_iterator pred_begin(const BasicBlock *BB) {
71  return pred_const_iterator(BB);
72}
73inline pred_iterator pred_end(BasicBlock *BB) { return pred_iterator(BB, true);}
74inline pred_const_iterator pred_end(const BasicBlock *BB) {
75  return pred_const_iterator(BB, true);
76}
77
78
79
80//===--------------------------------------------------------------------===//
81// BasicBlock succ_iterator definition
82//===--------------------------------------------------------------------===//
83
84template <class _Term, class _BB>           // Successor Iterator
85class SuccIterator : public std::bidirectional_iterator<_BB, ptrdiff_t> {
86  const _Term Term;
87  unsigned idx;
88public:
89  typedef SuccIterator<_Term, _BB> _Self;
90  // TODO: This can be random access iterator, need operator+ and stuff tho
91
92  inline SuccIterator(_Term T) : Term(T), idx(0) {         // begin iterator
93    assert(T && "getTerminator returned null!");
94  }
95  inline SuccIterator(_Term T, bool)                       // end iterator
96    : Term(T), idx(Term->getNumSuccessors()) {
97    assert(T && "getTerminator returned null!");
98  }
99
100  inline bool operator==(const _Self& x) const { return idx == x.idx; }
101  inline bool operator!=(const _Self& x) const { return !operator==(x); }
102
103  inline pointer operator*() const { return Term->getSuccessor(idx); }
104  inline pointer operator->() const { return operator*(); }
105
106  inline _Self& operator++() { ++idx; return *this; } // Preincrement
107  inline _Self operator++(int) { // Postincrement
108    _Self tmp = *this; ++*this; return tmp;
109  }
110
111  inline _Self& operator--() { --idx; return *this; }  // Predecrement
112  inline _Self operator--(int) { // Postdecrement
113    _Self tmp = *this; --*this; return tmp;
114  }
115};
116
117typedef SuccIterator<TerminatorInst*, BasicBlock> succ_iterator;
118typedef SuccIterator<const TerminatorInst*,
119                     const BasicBlock> succ_const_iterator;
120
121inline succ_iterator succ_begin(BasicBlock *BB) {
122  return succ_iterator(BB->getTerminator());
123}
124inline succ_const_iterator succ_begin(const BasicBlock *BB) {
125  return succ_const_iterator(BB->getTerminator());
126}
127inline succ_iterator succ_end(BasicBlock *BB) {
128  return succ_iterator(BB->getTerminator(), true);
129}
130inline succ_const_iterator succ_end(const BasicBlock *BB) {
131  return succ_const_iterator(BB->getTerminator(), true);
132}
133
134
135
136//===--------------------------------------------------------------------===//
137// GraphTraits specializations for basic block graphs (CFGs)
138//===--------------------------------------------------------------------===//
139
140// Provide specializations of GraphTraits to be able to treat a function as a
141// graph of basic blocks...
142
143template <> struct GraphTraits<BasicBlock*> {
144  typedef BasicBlock NodeType;
145  typedef succ_iterator ChildIteratorType;
146
147  static NodeType *getEntryNode(BasicBlock *BB) { return BB; }
148  static inline ChildIteratorType child_begin(NodeType *N) {
149    return succ_begin(N);
150  }
151  static inline ChildIteratorType child_end(NodeType *N) {
152    return succ_end(N);
153  }
154};
155
156template <> struct GraphTraits<const BasicBlock*> {
157  typedef const BasicBlock NodeType;
158  typedef succ_const_iterator ChildIteratorType;
159
160  static NodeType *getEntryNode(const BasicBlock *BB) { return BB; }
161
162  static inline ChildIteratorType child_begin(NodeType *N) {
163    return succ_begin(N);
164  }
165  static inline ChildIteratorType child_end(NodeType *N) {
166    return succ_end(N);
167  }
168};
169
170// Provide specializations of GraphTraits to be able to treat a function as a
171// graph of basic blocks... and to walk it in inverse order.  Inverse order for
172// a function is considered to be when traversing the predecessor edges of a BB
173// instead of the successor edges.
174//
175template <> struct GraphTraits<Inverse<BasicBlock*> > {
176  typedef BasicBlock NodeType;
177  typedef pred_iterator ChildIteratorType;
178  static NodeType *getEntryNode(Inverse<BasicBlock *> G) { return G.Graph; }
179  static inline ChildIteratorType child_begin(NodeType *N) {
180    return pred_begin(N);
181  }
182  static inline ChildIteratorType child_end(NodeType *N) {
183    return pred_end(N);
184  }
185};
186
187template <> struct GraphTraits<Inverse<const BasicBlock*> > {
188  typedef const BasicBlock NodeType;
189  typedef pred_const_iterator ChildIteratorType;
190  static NodeType *getEntryNode(Inverse<const BasicBlock*> G) {
191    return G.Graph;
192  }
193  static inline ChildIteratorType child_begin(NodeType *N) {
194    return pred_begin(N);
195  }
196  static inline ChildIteratorType child_end(NodeType *N) {
197    return pred_end(N);
198  }
199};
200
201
202
203//===--------------------------------------------------------------------===//
204// GraphTraits specializations for function basic block graphs (CFGs)
205//===--------------------------------------------------------------------===//
206
207// Provide specializations of GraphTraits to be able to treat a function as a
208// graph of basic blocks... these are the same as the basic block iterators,
209// except that the root node is implicitly the first node of the function.
210//
211template <> struct GraphTraits<Function*> : public GraphTraits<BasicBlock*> {
212  static NodeType *getEntryNode(Function *F) { return F->getEntryNode(); }
213};
214template <> struct GraphTraits<const Function*> :
215  public GraphTraits<const BasicBlock*> {
216  static NodeType *getEntryNode(const Function *F) { return F->getEntryNode(); }
217};
218
219
220// Provide specializations of GraphTraits to be able to treat a function as a
221// graph of basic blocks... and to walk it in inverse order.  Inverse order for
222// a function is considered to be when traversing the predecessor edges of a BB
223// instead of the successor edges.
224//
225template <> struct GraphTraits<Inverse<Function*> > :
226  public GraphTraits<Inverse<BasicBlock*> > {
227  static NodeType *getEntryNode(Inverse<Function*> G) {
228    return G.Graph->front();
229  }
230};
231template <> struct GraphTraits<Inverse<const Function*> > :
232  public GraphTraits<Inverse<const BasicBlock*> > {
233  static NodeType *getEntryNode(Inverse<const Function *> G) {
234    return G.Graph->front();
235  }
236};
237
238#endif
239